1. Field of the Invention
This invention relates generally to automatic machinery for cambering or curving, in accordance with a predetermined configuration, thin rectilinear metal elements of constant thickness, such as wires, tubes, or metal strips.
2. Description of the Related Art
Machines are known which feed metal wires and the like stepwise from a distributor means to a bending means, just downstream, which is rotated by one drive mechanism about an axis perpendicular to the feed direction and reciprocated by a second drive mechanism along a linear path parallel to this axis. The first and second drive mechanisms are synchronized with the feed device in a predetermined operational sequence.
Curving machines of this type are popular because of their automatic operation and because they make it possible to curve wires and the like continuously.
The use of such machines is generally directed to the manufacture of bent wire articles. In these machines the rotation of the bending means is produced, in each bending cycle, between the outgoing and incoming travel of the reciprocal movement of the bending means.
With this sequence of motions it is possible first to bring the bending means into lateral contact with the wire segment emerging from the distributor means, then to rotate it through a certain angle in one direction or the other so that it bends this wire segment about the exit point of the distributor means, and finally to retract it so as to allow the wire to advance for the next bending cycle. The degree of bending of the wire depends upon the angle through which the bending means rotate, whereas the length of the bent wire segment is determined by the pitch of the feed device.
The essential mechanical element used in the construction of a curving machine of this known type is formed by a cylindrical bending head whose axis of symmetry is perpendicular to the feed direction of the wire to be curved. On its face turned towards the outlet of the distributor means, this head supports the bending means properly speaking which is formed by a fixed finger off-centered with respect to the axis of symmetry of the head; the reciprocal movement of this bending means is provided by the action of a cylinder and piston device which moves the whole bending head whereas its angular rotation is produced by a stepper motor which causes the bending head to rotate about its axis of symmetry.
In this first known machine, the particular structure of the bending means and of the drive means therefor is the cause of a number of drawbacks.
The first of these drawbacks results from the considerable inertia of the bending head which opposes the translational movement of this latter by causing a delay in responding to actuation of the cylinder and piston device, which delay is prejudicial to the working speed and consequently to the productivity of the curving machine.
Another drawback is inherent in the motor for angularly rotating the bending head which is not sufficiently accurate for some applications of the curving machine.
But the main drawback of this known curving machine, as can be seen from the above description of its operation, resides in the fact that it can only produce wires whose bends extend in one and the same plane perpendicular to the axis of rotation of the bending means. In other words, it is not adapted to curving wires in all directions in space. Now, in numerous fields of application and more particularly in the manufacture of frames or skeletons for motor vehicle seats, metal wires are required bent according to a spatial configuration.
To manufacture such wires, multiple slide machines are at the present time available. In these machines, the slides which are mounted side by side on the frame of the machine comprise bending heads of different shapes cooperating with complementary counter matrices and may be orientated in any direction in space. Thus, a wire placed between the bending heads of the slides and the associated counter matrices may be curved, after actuating the slides, according to a spatial configuration which is defined by the orientation and the working travel of the slides as well as by the form of their bending head.
It will be readily understood that this multi-slide machine is only interesting for curving wires of great length.
Moreover, its efficieny is only effective in the case of large scale manufacture since, whenever it is desired to change the configuration or the bending pattern of the wire, it is necessary to replace the slides in position by slides specially adapted to the new manufacture contemplated, then to adjust the operation of these latter, this double operation possibly taking two to three hours. In addition, this multi-slide machine requires very expensive tooling.